The present invention relates generally to an apparatus for controlling the temperature in a cooling circulation of a combustion motor, such as that in a vehicle, of the type which includes a thermostatic valve for controlling the cooling medium flow from the combustion motor through a direct return and/or via a heat exchanger back to the combustion motor. More particularly, the present invention relates to thermostatic controls responsive to the motor temperature as well as other control variables, such as the temperature of the exterior environment.
It has been long known to control the temperature of the cooling medium and, thereby, the temperature of the combustion motor, especially during the start of the combustion motor, by providing a thermostatic valve which is so adjusted that the connection to the heat exchanger is opened up only after a predetermined temperature below the operating temperature is achieved by the cooling medium. The combustion motor is thus warmed to its operating temperature in the shortest possible time.
The temperature of the exterior environment has a significant influence on the warm-up time. The operating temperature is reached more quickly when the exterior temperature is higher than when the exterior temperature is lower. A thermostatic valve which opens at a temperature which is too far beneath the operating temperature retards the achievement of the operating temperature, especially with low exterior temperatures. With low exterior temperature it is therefore desired that the thermostatic valve open first at a higher cooling medium temperature. With high exterior temperatures, this thermostatic valve should, however, be open at a significantly lower temperature so that the operating temperature of the motor is not over-shot. Such a thermostatic valve has been recognized as a desirable feature in combustion motors for some time. Previous devices which sought to achieve this result include the so-called winter-thermostatic valves for lower outside temperatures and summer thermostatic valves for higher outside temperatures. However, these devices require additional servicing procedures and, more importantly, present a danger of motor damage because of an incorrect selection of the proper thermostatic valve.
In order to solve the above-described problem, it has also been known to create a unitary apparatus which is adjustable to correspond to the exterior temperature. None of the previously known unitary devices has, however, found extensive use in practice because of their excessive costs and low reliability. For example, DE-OS No. 14 51 669 (German published application) provides two thermostatic working elements which interchangably or consecutively come into operation. The relative position with respect to the valve plate of these two thermostatic working elements individually or together is changeable, thus making relative movement within the thermostat necessary. Such movement results in increased production costs as well as the problem of providing a guidance member between the valve plate and thermostatic working elements. This guidance member is very sensitive to disturbance and must be constructed within close dimensional tolerances.
An object of the present invention is the provision of a mechanically simple and functionally reliable thermostatic valve for combustion motors.
Another object is to provide a thermostatic control responsive to motor temperature as well as the exterior temperature and other operating parameters.
These and other objects of the present invention are obtained in an adjustable abutment which forms a support for the working piston of the thermostat so that the distance to the valve plate housing is adjustable. By changing the relative position of the abutment with respect to the thermostatic working element, it is possible to change the working temperature region of the thermostatic valve. A basic structural change in conventional valve constructions is, thus, not necessary. Further, the working region can be switched not only to extreme positions, but also intermediate positions, so that an efficient thermostatic control is possible taking into account exterior temperatures as well as other operating conditions, such as exhaust temperature, motor rotational speed or rational movement, oil temperature, and the pressure differential in a vacuum pipe. It is possible in view of these factors to change the motor temperature within certain limits in order to optimize the operation of the combustion motor.
Other objects, advantages, and novel features of the present invention will become apparent from the following detailed description of the preferred embodiments when considered in conjuction with the drawings.